1. Field of the Invention
The present invention relates to an imaging apparatus capable of photographing using a stroboscope apparatus and to a lighting control method of the imaging apparatus.
2. Description of the Related Art
In general, a test flash system for performing a test flash (pre-flash) for lighting control before a main flash to measure reflected light of a subject in advance and calculating a main flash quantity from the measurement result is known as a lighting control system, for a stroboscope apparatus using a xenon tube. A test flash quantity is preset in initially set exposure (for example, aperture value F2.8, shutter speed 1/60, and ISO 100) so that a desired light quantity reaches a predetermined distance (FIG. 3).
Japanese Patent Laid-Open No. 2008-219334 describes a configuration in lighting control using a test flash, wherein the distance from the subject is taken into account to adjust the sensitivity at the test flash to reduce arithmetic errors of exposure.
Meanwhile, if the exposure at the test flash is deviated too much from the exposure at the main flash, the effect on the subject by the ambient light may be changed, and the lighting control accuracy may be affected. For example, in a scene in which the exposure at the main flash is set to F2.8, shutter speed 1/2000, and ISO 100 as in FIG. 4, blown out highlights may occur in the subject at the exposure with the initial setting described above, even without the illumination by the test flash. If the blown out highlights occur in the subject, the subject is always overexposed, and an appropriate reflection luminance is not obtained by the test flash (no luminance difference before and after the test flash). Therefore, it is desirable to set the exposure at the test flash to about the same level as the exposure at the main flash in order to maintain the accuracy of lighting control calculation.
However, if the exposure at the test flash is different from the exposure at the initial setting, the reflection luminance may turn out to be higher or lower with the preset test flash quantity as shown in FIGS. 5B and 5C, and proper lighting control is not performed for the subject in some cases. The light quantities of the test flash and the main flash are correlated in a xenon tube, and a main flash table needs to be included for each flash quantity of the test flash. Therefore, a plurality of corresponding main flash tables need to be held to allow performing the test flash based on a plurality of types of flash quantity. However, it is difficult in reality to hold the plurality of main flash tables, due to the memory capacity of the imaging apparatus. More specifically, it is not realistic to apply a plurality of types of flash quantity to the test flash in an imaging apparatus using a stroboscope apparatus including a xenon tube as a light source.